/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j.io;

import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

/**
 * <p> <code>SAXHelper</code> contains some helper methods for working with
 * SAX and XMLReader objects. </p>
 * 
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.2 $
 */
class SAXHelper
{
   private static boolean loggedWarning = true;

   protected SAXHelper()
   {
   }

   public static boolean setParserProperty(XMLReader reader,
      String propertyName, Object value)
   {
      try
      {
         reader.setProperty(propertyName, value);

         return true;
      }
      catch(SAXNotSupportedException e)
      {
         // ignore
      }
      catch(SAXNotRecognizedException e)
      {
         // ignore
      }

      return false;
   }

   public static boolean setParserFeature(XMLReader reader, String featureName,
      boolean value)
   {
      try
      {
         reader.setFeature(featureName, value);

         return true;
      }
      catch(SAXNotSupportedException e)
      {
         // ignore
      }
      catch(SAXNotRecognizedException e)
      {
         // ignore
      }

      return false;
   }

   /**
    * Creats a default XMLReader via the org.xml.sax.driver system property or
    * JAXP if the system property is not set.
    * 
    * @param validating DOCUMENT ME!
    * 
    * @return DOCUMENT ME!
    * 
    * @throws SAXException DOCUMENT ME!
    */
   public static XMLReader createXMLReader(boolean validating)
      throws SAXException
   {
      XMLReader reader = null;

      if(reader == null)
      {
         reader = createXMLReaderViaJAXP(validating, true);
      }

      if(reader == null)
      {
         try
         {
            reader = XMLReaderFactory.createXMLReader();
         }
         catch(Exception e)
         {
            if(isVerboseErrorReporting())
            {
               // log all exceptions as warnings and carry
               // on as we have a default SAX parser we can use
               System.out.println("Warning: Caught exception attempting "
                  + "to use SAX to load a SAX XMLReader ");
               System.out.println("Warning: Exception was: " + e);
               System.out.println("Warning: I will print the stack trace "
                  + "then carry on using the default " + "SAX parser");
               e.printStackTrace();
            }

            throw new SAXException(e);
         }
      }

      if(reader == null)
      {
         throw new SAXException("Couldn't create SAX reader");
      }

      return reader;
   }

   /**
    * This method attempts to use JAXP to locate the SAX2 XMLReader
    * implementation. This method uses reflection to avoid being dependent
    * directly on the JAXP classes.
    * 
    * @param validating DOCUMENT ME!
    * @param namespaceAware DOCUMENT ME!
    * 
    * @return DOCUMENT ME!
    */
   protected static XMLReader createXMLReaderViaJAXP(boolean validating,
      boolean namespaceAware)
   {
      // try use JAXP to load the XMLReader...
      try
      {
         return JAXPHelper.createXMLReader(validating, namespaceAware);
      }
      catch(Throwable e)
      {
         if(!loggedWarning)
         {
            loggedWarning = true;

            if(isVerboseErrorReporting())
            {
               // log all exceptions as warnings and carry
               // on as we have a default SAX parser we can use
               System.out.println("Warning: Caught exception attempting "
                  + "to use JAXP to load a SAX XMLReader");
               System.out.println("Warning: Exception was: " + e);
               e.printStackTrace();
            }
         }
      }

      return null;
   }

   protected static boolean isVerboseErrorReporting()
   {
      try
      {
         String flag = System.getProperty("org.dom4j.verbose");

         if((flag != null) && flag.equalsIgnoreCase("true"))
         {
            return true;
         }
      }
      catch(Exception e)
      {
         // in case a security exception
         // happens in an applet or similar JVM
      }

      return true;
   }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
